The set of 20 steel mandrels provided with the Jump Ring Maker is now available separately. Each mandrel is 3-7/8" long overall and will form a coil up to 3" long. Mandrels range in diameter from 2.5 mm to 12 mm in increments of 1/2 mm. The mounting end of each of the larger mandrels is stepped down to 8.9 mm (11/32").